For ease of understanding and simplicity in explanation, the present invention will be described using primarily the production of synthetic filaments. This use of synthetic filament production is not intended to limit the invention to this field. It is believed that the present invention may be applied to any operation that involves off-winding, especially those operations where speed and efficiency are advantageous.
Synthetic filaments are traditionally produced by various spinning techniques. For example, synthetic filaments may be melt-spun by extruding a melt-spinnable polymer through relatively small-sized orifices in a spin pack to form streams of filaments that are substantially immediately solidified in a quench cabinet. The filaments are thereafter continuously taken up by a high-speed winder to form a generally cylindrical package. Depending on the intended end use, the filaments may be flat (undrawn) or may be subjected to a drawing step prior to being taken up to form the package.
Typically, a plurality of filaments will form a yarn end associated with each threadline. The yarn ends of each threadline are subsequently wound by a high-speed winder to form respective yarn packages. Common take-up methods guide each yarn end through a respective traversing arm associated with the high-speed winder. The traversing arm reciprocates at a relatively high speed linearly parallel to the longitudinal axis of a rotating yarn package core. As a result, the traversing arm causes the yarn end guided thereby to be wound in alternating layers of reverse helical directions about the core as the yarn package is "built" (i.e., as the radial dimension of the yarn package increases due to the yarn end wound thereabout in alternating reverse helical layers).
It was the conventional wisdom in this art that, as a practical matter, only a single yarn end could be wound around the yarn package core. This was because it was believed that the traversing arm would cause commingling to occur between the multiple yarn ends. Such yarn end commingling would prevent the later separation of the individual yarns from the yarn package and their individual use during downstream processing (e.g., as might be needed for a beam warping operation).
However, according to U.S. Pat. No. 5,665,293 (the entire content of which is expressly incorporated herein by reference), there are provided a novel yarn package and method of forming the same, wherein multiple yam ends are wound into a generally cylindrical yarn package without commingling occurring between the individual yarn ends. The multiple yarn ends may thus be separated easily from one another during off-winding.
Now, the off-winding of such multiple yarn end packages presents several technical challenges. For example, the multiple yarn ends cannot simply be pulled from the end of the yarn package (as is customary during creeling operations of single yarn end packages) because the yarn ends would become twisted around one another, preventing their separation. Thus, off-winding assemblies and methods are needed that are especially adapted to off-wind yarn packages formed of multiple yarn ends to ensure that the yarn ends are efficiently separated from one another during off-winding operations. It is toward providing such off-winding assemblies and methods that the present invention is directed.
In conventional off-winding processes, regardless of the number of ends being off-wound, the package rotates from the motive force provided by off-winding (or is mechanically driven (rotated)) and requires braking of the package support. Thus, if the re-winder (which provides the motive force) stops, the package must also stop. Failure to mechanically brake the movement of the package results in waste, either of thread that is unwound and tangled or labor to untangle the unwound thread. Typically, this thread cannot be saved because the consistency of the rewinding process is lost in such cases and, if the stoppage occurs in the middle of rewinding, even the rewound product could be lost. The need for actuated mechanical braking of the package limits the capabilities, e.g., speed, of the off-winding process. For example, the higher the speed, the greater the braking action required to stop the package.
U.S. Pat. No. 2,285,667, to Kontz, Jr. describes off-winding two threadlines from a single package by routing one threadline through the center of the package and the other threadline off through the traveler and a guide. Such processes are limited to relatively low (less than about 200 meters/min.) backwinding speed because the friction on the guides that direct the threadline through the center can break the threadline.